traitorous (adj.)

c. 1200, "one who betrays a trust or duty," from Old French traitor, traitre "traitor, villain, deceiver" (11c., Modern French traître), from Latin traditor "betrayer," literally "one who delivers," agent noun from stem of tradere "deliver, hand over," from trans- "over" (see trans-) + dare "to give" (from PIE root *do- "to give"). Originally usually with a suggestion of Judas Iscariot; especially of one false to his allegiance to a sovereign, government, or cause from late 15c. Compare treason, tradition.